The present invention relates to an image reading apparatus such as a facsimile machine or a scanner, a document transport apparatus for feeding a document (sheet such as paper or a film sheet) into an image reading section of the image reading apparatus and for discharging the document after an image is read, and a document transport method.
In general, an image reading apparatus includes a document transport apparatus for transporting a document to an image reading section. The document transport apparatus may be a device separate from the image reading apparatus and can be installed on the image reading apparatus. Such a document transport apparatus generally transports the uppermost document stacked on a sheet feeding tray one by one and sequentially feeds and sets the sheet at a reading position of the image reading section. The document transport apparatus is configured to feed the document to the reading position after one side of the document is read, so that both sides of the document are read.
Japanese Patent Publication (Kokai) No. 2002-362778 and Japanese Patent No. 3329852 have disclosed a document transport apparatus in which a document is turned upside down as well as reversed front to back after the document is read in a one-side processing or a both-side processing, so that an order of the documents is maintained same as that on the sheet feeding tray when the document is discharged.
In the document transport apparatus disclosed in Japanese Patent Publication (Kokai) No. 2002-362778, a curved return path is provided at a discharge side for reading both sides of the document, and a roller path with a large-diameter roller is provided for guiding the document to the return path. After a front side of the document is read, the document passes through the roller path and the return path to be turned upside down, and returns to a reading section. In the document transport apparatus disclosed in Japanese Patent No. 3329852, a loop-shaped turning section is provided on a sheet feeding side. After a front side of the document is read, the document returns to the sheet feeding side to be turned upside down in a large loop, and returns to a reading section.
In the document transport apparatuses described above, when only one side of the document is read, the document is turned upside down and switched back, and is turned upside down again, so that the document is discharged in an aligned state.
In the document transport apparatus disclosed in Japanese Patent Publication (Kokai) No. 2002-362778, the larger-diameter roller is provided at an upstream side of the reading section for turning the document upside down and returning the document to the reading section. Accordingly, the apparatus main body has a large length in a lateral direction (document transport direction). In the document transport apparatus disclosed in Japanese Patent No. 3329852, the loop-shaped turning section is provided for turning the document upside down before the document is transported to the sheet feeding side. Accordingly, similarly to the apparatus in Japanese Patent Publication (Kokai) No. 2002-362778, the apparatus main body has a large length in the lateral direction.
That is, in the conventional document transport apparatus, if only one side of the document is read and the document is discharged orderly, the whole apparatus does not need to have a large length in the lateral direction. However, if it is necessary to read both sides of the document, the conventional document transport apparatus inevitably has a large size.
In view of the problems described above, the present invention has been made, and an object of the present invention is to provide a document transport apparatus as well as a document transport method in which both sides of the document can be read and the document can be discharged in an original order. Further, the document transport apparatus has a short length in the lateral direction.
Another object of the present invention is to provide an image reading apparatus having such a document transport function.
Further objects and advantages of the invention will be apparent from the following description of the invention.